In marine engines, whether of the outboard or the inboard type, a portion of the engine housing extends below the water line so that the propeller can be located below the surface of the water. The portion of the engine housing which extends below the water surface includes a chamber for housing gears which transfer power from an engine drive shaft to the propeller shaft. This chamber is sealed and filled with oil to lubricate the gears.
One problem associated with this type of engine is maintaining the integrity of the seal of the oil-filled chamber which may be breached, often by the entanglement of fishing line in the propeller shaft, allowing oil within the casing to escape and water from the surrounding environment to leak into the system. Water associated with oil surrounding the moving parts of a marine engine can ultimately cause damage, reducing the ability of the oil in the sealed chamber to lubricate the moving parts and causing rust or other deterioration of the casing and the elements contained therein. Along with the loss of oil from the system, this can cause excess wear on the gears and the other engine components. Eventually, the gradual wear on the gears and other engine components, if undetected, may result in engine failure. The costs associated with the repair of an engine due to loss of oil and/or inflow of water are expensive. Also, damage to the gear system can result in a loss of propeller function and cause inconvenience and possibly pose a danger to the marine vehicle and its occupants.